Question: Is ${78990}$ divisible by $4$ ?
Explanation: A number is divisible by $4$ if the last two digits are divisible by $4$ . [ Why? We can rewrite the number as a multiple of $100$ plus the last two digits: $ \gray{789} {90} = \gray{789} \gray{00} + {90} $ Because $78900$ is a multiple of $100$ , it is also a multiple of $4$ So as long as the value of the last two digits, ${90}$ , is divisible by $4$ , the original number must also be divisible by $4$ Is the value of the last two digits, $90$ , divisible by $4$ No, $90$ is not divisible by $4$, so $78990$ is also not divisible by $4$.